Quantifying the potential for dose reduction with visual grading regression.

OBJECTIVES: To propose a method to study the effect of exposure settings on image quality and to estimate the potential for dose reduction when introducing dose-reducing measures. METHODS: Using the framework of visual grading regression (VGR), a log(mAs) term is included in the ordinal logistic regression equation, so that the effect of reducing the dose can be quantitatively related to the effect of adding post-processing. In the ordinal logistic regression, patient and observer identity are treated as random effects using generalised linear latent and mixed models. The potential dose reduction is then estimated from the regression coefficients. The method was applied in a single-image study of coronary CT angiography (CTA) to evaluate two-dimensional (2D) adaptive filters, and in an image-pair study of abdominal CT to evaluate 2D and three-dimensional (3D) adaptive filters. RESULTS: For five image quality criteria in coronary CTA, dose reductions of 16-26% were predicted when adding 2D filtering. Using five image quality criteria for abdominal CT, it was estimated that 2D filtering permits doses were reduced by 32-41%, and 3D filtering by 42-51%. CONCLUSIONS: VGR including a log(mAs) term can be used for predictions of potential dose reduction that may be useful for guiding researchers in designing subsequent studies evaluating diagnostic value. With appropriate statistical analysis, it is possible to obtain direct numerical estimates of the dose-reducing potential of novel acquisition, reconstruction or post-processing techniques.

Quantifying the potential for dose reduction with visual grading regression.

Objectives To propose a method to study the effect of exposure settings on image quality and to estimate the potential for dose reduction when introducing dose-reducing measures. Methods Using the framework of visual grading regression (VGR), a log(mAs) term is included in the ordinal logistic regression equation, so that the effect of reducing the dose can be quantitatively related to the effect of adding post-processing. In the ordinal logistic regression, patient and observer identity are treated as random effects using generalised linear latent and mixed models. The potential dose reduction is then estimated from the regression coefficients. The method was applied in a single-image study of coronary CT angiography (CTA) to evaluate two-dimensional (2D) adaptive filters, and in an image-pair study of abdominal CT to evaluate 2D and three-dimensional (3D) adaptive filters. Results For five image quality criteria in coronary CTA, dose reductions of 16-26% were predicted when adding 2D filtering. Using five image quality criteria for abdominal CT, it was estimated that 2D filtering permits doses were reduced by 32-41%, and 3D filtering by 42-51%. Conclusions VGR including a log(mAs) term can be used for predictions of potential dose reduction that may be useful for guiding researchers in designing subsequent studies evaluating diagnostic value. With appropriate statistical analysis, it is possible to obtain direct numerical estimates of the dose-reducing potential of novel acquisition, reconstruction or post-processing techniques.

Fractures of the fifth metacarpal.

BACKGROUND: The literature is limited concerning the epidemiological issues of fracture in the fifth metacarpal bone. PURPOSE: To explore the incidence and types of this fracture, and how the fracture is related to age, gender, trauma mechanism, and at what day of the week the causing trauma occurred. MATERIAL AND METHODS: All hand fractures registered at the Department of Radiology, Buskerud Hospital, Norway, in the period between 2004 and 2006 were reviewed. RESULTS: Of 1475 hand fractures, 271 (18.4%) were located in the fifth metacarpal bone. In 130 of these cases (121 male, nine female), the trauma had occurred through aggression, such as a fistfight or from punching a hard object. The majority of fractures were located in the neck of the metacarpal bone (boxer's fracture). The median age of this group was 22 (7-51) years. Concerning the time of trauma, there was a significant peak during weekends (95 patients). One hundred forty-one of the fifth metacarpal fractures were caused by accidental trauma (99 males, 42 females). In this group, the fractures were located approximately equally in the subcapital, diaphyseal, and basal part of the metacarpal. The median age was 34 (2-90) years. The accidental traumas occurred about as often during the weekdays as during the weekend. CONCLUSION: Of all hand fractures, fractures of the fifth metacarpal bone are the most common. There are as many aggression-related fractures as accidental fractures in the fifth metacarpal bone. When the fracture is caused by aggression, the typical patient is a young male sustaining fracture during the weekend.

Genetic structuring in three closely related circumpolar plant species: AFLP versus microsatellite markers and high-arctic versus arctic-alpine distributions.

Genetic structuring in response to the glacial cycles has been investigated for many plant species, but exclusively high-arctic ones have not been studied. Such extremely cold-adapted species have probably experienced range reductions under the present climate. Here we compare three predominantly selfing species of Draba with different distributions and hardiness (D. subcapitata, high-arctic; D. nivalis, arctic to arctic-alpine; D. fladnizensis, arctic-alpine) for genetic structuring on the basis of two different types of molecular markers (10 microsatellite loci and 160 amplified fragment length polymorphisms (AFLPs)). The degree of genetic structuring within these species is of particular interest because it has been shown that they contain many cryptic biological species. The high-arctic D. subcapitata had less phylogeographic structure, less diversity and fewer private alleles than the other two species, suggesting that long-distance dispersal may occur more frequently in the high arctic, that hardy plants may have higher probability for establishment after dispersal under high-arctic conditions and that high-arctic species may have experienced a bottleneck during the present interglacial. In contrast, D. fladnizensis and D. nivalis showed distinct phylogeographic structure and more diversity, suggesting separate long-term refugia in Eurasia and North America/Beringia. The AFLP markers revealed more phylogeographic structuring than the microsatellites, possibly because of the higher number of loci surveyed and/or because structure at very large geographic scales is blurred by high mutation rate leading to homoplasy at microsatellite loci. The number of genetic groups detected was in any case insignificant compared with the numerous cryptic biological species known within these species, supporting rapid development of sterility barriers.

Acute osteomyelitis as a complication of varicella.

Varicella is a common viral infection in childhood, and acute osteomyelitis is one of the rare but serious complications. We report two cases of osteomyelitis as a complication of varicella. The possibilities and limitations of the different imaging modalities are discussed, as well as imaging findings during the course of this condition.

Analytical methods and stability assessment of liquid yeast derived sucrase.

Two independent analytical methods for determining the activity and stability profile of liquid yeast derived sucrase (YS) were established and validated in order to conduct preliminary stability studies as a function of temperature. The methods included a hexokinase-based (HK) enzymatic assay for determining the formation of glucose upon hydrolysis of sucrose by YS, and a direct polarimetric procedure to quantitate YS hydrolysis of sucrose. Both assays were validated with respect to YS dilution, incubation time, sucrose or glucose concentration, linearity of response and within- and between-day variability. A preliminary stability study was conducted over a 24 week period with liquid YS samples stored at -20, 4, 30, 40 and 50 degrees C. Enzymatic activity was monitored as a function of time using both the HK and polarimetric assays. Liquid YS samples stored at -20, 4 and 30 degrees C retained 100% activity after 24 weeks storage, while the samples stored at 40 degrees C lost approximately 70% activity over the same storage period and samples stored at 50 degrees C lost approximately 95% activity after 12 weeks storage. The two methods of analysis gave consistent results over the course of the study.

5-Aminosalicylic acid enema in the treatment of distal ulcerative colitis, proctosigmoiditis, and proctitis.

The efficacy and safety of 4-g 5-aminosalicylic acid enemas were assessed in 153 patients with ulcerative colitis involving up to 50 cm of distal colon. Seventy-six patients received active medication and 77 received a placebo. There were 20 dropouts (6 in the active group and 14 in the placebo group) during the study because of insufficient efficacy. After 6 wk of therapy, 48 of the 76 patients (63%) receiving 5-aminosalicylic acid were considered to be "much improved" by the study physician compared to 22 of the 77 patients (29%) on placebo (p = 0.001). A disease activity index based on patient symptoms and sigmoidoscopic appearance was used to assess efficacy. Mean disease activity index declined 55% for patients on 5-aminosalicylic acid and 24% for patients on placebo (p = 0.0001). Analysis of subgroups indicated that patients most likely to respond were those with disease confined to the 20-40 cm from the anus. Response was not affected by concurrent sulfasalazine, but patients requiring concurrent oral steroids had a diminished response. Rapid onset of efficacy was shown by a significant reduction in rectal bleeding within 3 days of treatment initiation. 5-Aminosalicylic acid enemas are well tolerated and are of benefit in the treatment of ulcerative colitis confined to the distal colon.

The effect of procaterol treatment on beta-adrenergic bronchodilation and polymorphonuclear leukocyte responsiveness.

Procaterol is a new and effective beta-adrenergic bronchodilator. To determine if procaterol administration could cause tachyphylaxis, airway and leukocyte beta-adrenergic function were monitored in 10 patients with asthma during two 4-wk, double-blind treatment periods, each preceded by a 2-wk beta-agonist washout. Treatment periods were randomized to placebo or procaterol (2 wk, 0.1 mg/day; 2 wk, 0.2 mg/day). At each 7 biweekly evaluations, the patient's cumulative bronchodilator dose-response to inhaled isoproterenol (0.1 to 0.64%) was measured, and venous blood was collected to quantitate, in vitro, the polymorphonuclear leukocyte (PMN) beta-adrenergic receptor's 125Iodo-cyanopindolol (125I-CYP) ligand binding and the PMN cyclic AMP response to isoproterenol and procaterol. Neither the airway nor leukocyte beta-adrenergic characteristics were changed during placebo treatment. Procaterol treatment reduced (p less than 0.05) the maximal 125I-CYP binding to PMN membranes but only during the initial 2 wk at low dosage. The percent PMN cyclic AMP increase to procaterol (10(-5) M) was also significantly (p less than 0.05) less during active treatment (141 +/- 40%) than during washout (256 +/- 24%) or placebo (257 +/- 32%). In contrast, procaterol treatment did not alter the acute isoproterenol bronchodilation response as measured by either the percent improvement in FEV1 or the dose required to produce 50% maximal bronchodilation. The duration of bronchodilation was not measured. Therefore, although procaterol therapy of asthma is associated with decreased PMN beta-adrenergic function, airway smooth muscle function appears not to be altered.

A placebo-controlled trial of procaterol: a new long-acting oral beta 2-agonist in bronchial asthma.

Procaterol hydrochloride, a potent beta 2-adrenergic bronchodilator developed in Japan, was evaluated in a double-blind, placebo-controlled study for efficacy and safety in 45 patients (ages 18 to 55 yr) with chronic documented reversible airway disease. After a 1-week placebo washout period, patients were administered either 0.05 mg or 0.10 mg of procaterol or placebo twice daily for 2 wk. Spirometric determinations, vital signs, and ECGs were obtained at 1/2, 1, 2, 4, 6, and 8 hr after the first dose and at the same time intervals after 1 and 2 wk of treatment. Patients recorded on a daily basis peak flow rates, asthma symptoms, need for supplemental aerosol, concurrent medications, and side effects. Spirometry results indicated significant improvement in pulmonary function with both doses of procaterol compared with placebo (P less than 0.05). The larger dose was generally more effective. Bronchodilatation was evident 1/2 hr after dosing and peaked at 2 hr. At 8 hr after 0.10 mg of procaterol, FEV1 was still above predose values. Daily peak flow rates were significantly higher with 0.10 mg than with 0.05 mg (P less than 0.05) and placebo (P less than 0.001). Tremor and nervousness were the most frequent side effects. They occurred in a dose-related frequency, were mild and transient, and occurred early in treatment. No significant drug-related changes were noted in ECGs, heart rate, blood pressure, or clinical laboratory data. Procaterol was found to be an effective, well-tolerated oral bronchodilator with a long duration of action, especially at 0.10 mg twice daily.

Controlled comparison of trebenzomine with doxepin as an antidepressant-anxiolytic.

Trebenzomine, a new psychotropic drug, was compared with doxepin in the treatment of anxiety and depression. The study was a three-week, double-blind trial involving 26 psychoneurotic inpatients. Multiple ratings by physician, nurse, and patient all concurred that the 2 drugs produced significant improvement in both depressive and anxious symptomatology. No significant differences were found between the 2 drugs either in terms of rate or degree of improvement or incidence of side effects. Further investigation of trebenzomine for anxious depression is warranted.

Ripazepam (CI-683): double-blind comparison with placebo in anxious patients.

Thirty anxious, neurotic patients were treated in a general practice setting with single-blind placebo for one week followed by two weeks of double-blind treatment with either placebo or 40 or 80 mg/day ripazepam (CI-683), a new potential antianxiety agent of the pyrazolodiazepinone series. As rated by both physician and patient, ripazepam was found significantly superior to placebo at both dosage levels. Some evidence of greater improvement at 80 mg/day than at 40 mg/day was also obtained. The drug appeared to be well tolerated, with side effects reported by only four patients.

Tolerance development to the effect of delta9-tetrahydrocannabinol on conditioned behavior: role of treatment interval and influence of microsomal metabolism.

The importance of frequency of administration in the development of tolerance to delta9-tetrahydrocannabinol (delta9-THC) was studied with repeated administration of the drug prior to behavioral test sessions at 1-, 3-, 7- or 14-day intervals. Partial tolerance was seen to develop to the depressant effects of delta9-THC (10mg/kg i.p.) on food-motivated performance on a variable interval 60-sec (VI 60) schedule of reinforcement. The tolerance was most evident with the most frequent exposure to the drug. No signs of increasing responsiveness to delta9-THC were seen with any of the four inter-injection intervals. The role of hepatic metabolism in tolerance to delta9-THC was tested by pretreating animals with SKF-525A, a microsomal enzyme inhibitor, or phenobarbital, a microsomal enzyme inducer. The dosing schedules for SKF-525A and phenobarbital were sufficient to alter hexobarbital sleeping time significantly, but they did not affect the normal VI 60 sec performance. After a 5 mg/kg dose of SKF-525A the depressant actions of 3 and 10 mg/kg doses of delta9-THC appeared to show a slight but consistent enhancement during the course of tolerance development. Phenobarbital (80 mg/kg/day) pretreatment for seven days blocked the acute behavioral depressant effect of 3 mg/kg of delta9-THC and appeared to enhance the development of tolerance. A metabolic mechanism of tolerance development was suggested by the data, but not demonstrated definitively.